Gas seal for rotary mechanisms



March 19, 1963 R. T. HURLEY 3,081,745

GAS SEAL FOR ROTARY MECHANISMS Filed May 3, 1961 2 Sheets-Sheet 1 FIG.I.

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ROY '1'. HLJRLEY 20 ATTORN EYS March 19', 1963 R. T. HURLEY 3,081,745

GAS SEAL FOR ROTARY MECHANISMS Filed May 3, 1961 2 Sheets- Sheet 2' F I3- 3 /W/fi /W////7///72 INVENTO ROY T- HLJR Y BY W flv ml five ATTORNEYS 3,081,745 GA SEAL FOR ROTARY MECHANESMS Roy T. Hurley, SantaBarbara, Calif., assignor to Curtiss- Wright Corporation, a corporationof Delaware Filed May 3, I961, Ser. No. 107,501 2 Claims. (Cl. 121-68)This invention relates to sealing means for rotary mechanisms and moreparticularly to gas sealing means for improving sealing characteristicsof the mechanism and helping insure relatively trouble-free and smoothfunctioning of the mechanism.

Although this invention is applicable to and useful in almost any typeof rotary mechanism, which presents a gas sealing requirement, such ascombustion engines, fluid motors, fluid pumps, compressors, and thelike, it is particularly useful in rotating combustion engines. Tosimplify and clarify the explanation of the invention, the descriptionwhich follows -will, for the most part, be restricted to the use of theinvention in a rotating combustion engine. It will be apparent from thedescription, however, that with slight variations, which would beobvious to a person skilled in the art, the invention is equallyapplicable to other types of rotary mechanisms.

The present invention is particularly useful in rotating combustionengines of the type which comprise an outer body having an axis,axially-spaced end walls, and a peripheral wall interconnecting the endwalls. In such rotary mechanisms the inner surfaces of the peripheralwall and end walls form a cavity, and the mechanism also includes aninner body or rotor which is mounted within the cavity between its endwalls.

The axis of the rotor is eccentric from and parallel .to the axis of thecavity of the outer body, and the rotor has axially-spaced end facesdisposed adjacent to the end walls of the outer body and a plurality ofcircumferentially-spaced apex portions. The rotor is rotatable relativeto the outer body such that the apex portions continuously engage theinner surface of the outer body to form a plurality of working chamberswhich vary in volume during engine operation, as a result of relativerotation between the rotor and the outer body.

The inner surface of the peripheral wall of the outer body has amulti-lobed profile which is preferably an epitrochoid and the number oflobes of this epitrochoid is one less than the number of apex portionsof the inner body or rotor.

By suitable arrangement of ports, such rotary mechanisms may be used asfluid motors, compressors, fluid pumps, or internal combustion engines.The invention is of particular importance when employed with a rotarymechanism which is designed for use as a rotating combustion engine,and, accordingly, will be described in combination with such an engine.As the description proceeds, however, it will be apparent that theinvention is not limited to this specific application.

When the rotary mechanism is designed for use as a rotating combustionengine, such engines also include an intake passage means for admittinga fuel-air mixture to the variable volume working chambers, an exhaustpassage means communicating with the working chambers, and suitableignition means so that during engine operation the working chambers ofthe engine undergo a cycle of operation which includes the four phasesof intake, compression, expansion and exhaust. This cycle of operationis achieved as a result of the relative rotation of the inner body orrotor and outer body and for this purpose both the inner body or rotorand outer body may rotate at different speeds, but preferably the innerbody or rotor rotates while the outer body is stationary.

For efficient operation of the engine, its Working cham- Patented Mar.19, 1953 bers should be sealed, and therefore, an effective seal isprovided between each rotor apex portion and the inner surface of theperipheral wall of the outer body, as well as between the end faces ofthe rotor and the inner surfaces of the end walls of the outer body.

Between the apex portions of its outer surface the rotor has a contourwhich permits its rotation relative to the outer body free of mechanicalinterference with the multi-lobed inner surface of the outer body. Themaximum profile which the outer surface of the rotor can have betweenits apex portions and still be free to rotate without interference isknown as the inner envelope of the multi-lobed inner surface, and theprofile of the rotor which is illustrated in the accompanying drawingsapproximates this inner envelope.

For purposes of illustration, the following description will be relatedto the present preferred embodiment of the engine in which the innersurface of the outer body defines a two-lobed epitrochoid, and in whichthe rotor or inner body has three apex portions and is generallytriangular in cross section but has curved or arcuate sides.

It is not intended that the invention be limited, however, to the formin which the inner surface of the outer body approximates a two-lobedepitrochoid and the inner body or rotor has only three apex portions. Inother embodiments of the invention the inner surface of the outer bodymay have a different plural number of lobes with a rotor having one moreapex portion than the inner surface of the outer body has lobes.

The operating cycle of the engine may include at least the phases ofintake, compression, expansion and exhaust and it will be readilyapparent, to those with ordinary skill in the art, that it is necessarythat the working chambers be sealed from each other during the operatingcycle of the engine. In order to prevent loss of pressure and fuelduring the compression phase and loss of power during the expansionphase, it is obviously of paramount importance that there be no leakageof gas between the inner member or rotor and the end faces of the outerbody. Should there be such leakage, either in the areas between apexesor at the apexes themselves, poor engine performance, loss of efiiciencyand malfunctioning would result.

There are known several prior types of gas seals which have been used inrotary mechanisms. For example, the gas has been sealed within and atthe adjacent end walls of the working chambers through use of relativelythick and rigid seals. Because of their relative rigidity it wasdifficult for such prior seals to adapt themselves to variations in theflatness of the end walls of the outer member caused by productiontolerances or thermal distortions. Also it was generally necessary toprovide an additional spring means to maintain the seal in sealingcontact with the end wall. Some of these prior seals were of a segmentaltype thus having a plurality of parts.

it is, therefore, an object of this invention to provide a novel andsimple gas :seal which is inexpensive to manufacture and expeditiouslyassembled.

It is a still further object of the present invention to provide a sealwherein there is endless contact between the seal and the end walls ofthe outer body.

Another object of the present invention is to provide a gas seal whichis flexible enough to adapt itself to variations in the end wall of theouter member.

It is still another object of the present invention to provide a gasseal which is normally biased toward and in engagement with the innerwall of the outer member.

A still further object of the present invention is to provide a gas sealwhich will not be subjected to the destructive eflect of hightemperature combustion gases.

Another object of the present invention is to provide a gas seal whichachieves effective sealing at the apexcs and substantially reducesblowby.

A further object of the present invention is to provide a gas sealwherein gas pressure is used to increase the sealing contact area.

Another object of the present invention is to provide a seal which isassembled by means so that the temperature rise to which the rotor andsealing means is sub jected will be used to increase sealing contactbetween the gas seal and the outer body.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention, theobjects and ad vantages being realized and attained by means of theinst-rumentalities and combinations particularly pointed out in theappended claims.

Briefly described, the present invention provides means for continuouslyengaging in gas sealing contact the inner surfaces of the end walls ofthe outer member.

As herein embodied, this means comprises a thin, flexible, triangularshaped, single piece sheet metal gas seal with an L-shaped cross sectionwhich is carried by the inner member and is in gas sealing contact withthe inner faces of the end wall of the outer member.

The invention consists in the novel parts, constructions, arrangements,combinations, and improvements shown and described.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one embodiment of the inventionand, together with the description, serve to explain the principles ofthe invention.

Of the drawings:

FIGURE 1 is a side elevation of the mechanism with the end wall of theouter body removed to show the rotor positioned within the outer bodyand wherein portions of the rotor and outer body are shown partially insection;

FIGURE 2 is a central vertical section of the mechanism taken along line2--2 of FIGURE 1 in which the rotor and outer body are shown in sectionand the shaft and eccentric are shown without section;

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 1 showingthe gas seal in relation to the apex seal;

, FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 1 showingthe gas seal in relation to the inner end wall of the outer body.

FIGURE 5 is a sectional View taken along line 5-5 of FIGURE 1 showingone method of securing the gas seal to the rotor.

FIGURE 6 is a plan view of the gas seal.

It is to be understood that both the foregoing general description andthe following detailed description are examplary and explanatory but arenot restrictive of the invention.

In the description which follows it is to be recognized that in practiceeither the outer body or the inner rotor may rotate while the othermember remains fixed or stationary, or both members may rotate as longas there is relative rotation between them to provide variable volumeworking chambers. In the description of the present preferredembodiment, for purposes of clarity, the invention will be describedwith reference to a rotary mechanism in which the outer body or housingis stationary and the inner body or rotor is rotatable.

Reference will now be made in detail to the present preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawings. As shown in FIGURE 1, a generally triangular rotor 10 havingarcuate sides is eccentrically supported for rotation Within an outerbody 12. Although in the illustrative embodiment shown in the drawingsthe outer body 12 is fixed or stationary, a practical and useful form ofthe invention may be constructed in which both the outer body and rotorare rotary, but the eccentric is stationary; in this latter form of theinvention the power shaft is driven directly by the rotation of theouter body and the inner rotor rotates relative to the outer body.

As shown in FIGURES 1 and 2, the rotor 10 rotates on an axis 14 which iseccentric from and parallel to the axis 16 of the curved inner surfaceof the outer body I2. The distance between the axis 14 and I6 is equalto the effective eccentricity of the engine and is designated e in thedrawings. The curved inner surface 1 8 of the outer body 12 hasbasically the form of an epitrochoid in geometric shape and includes twoarched lobe-defining portions, or lobes.

As embodied, the generally triangular shape of the rotor 10 correspondsin its configuration to the inner envelope or the maximum profile of therotor which will permit interference-free rotation of the rotor 10within the outer body 12.

In the form in the invention illustrated, the outer body 12 comprises aperipheral wall 28 which has for its inner surface the curved innersurface 1 8, and a pair of axially-spaced end walls 22 and 24 which aredisposed on opposite sides of the peripheral wall 20.

The end walls 22 and 24 support a shaft 26, the geometric center ofwhich is coincident with the axis 16 of the outer body 12. This shaft 26is supported for rotation by the end walls 22 and 24 on large and amplebearings 28. A shaft eccentric 30 is rigidly attached to or forms anintegral part of the shaft 26, and the rotor 10 is supported forrotation or rotatively mounted upon the shaft eccentric 30 by a rotorbearing 32 which is fixed to the rotor.

As shown in FIGURES 1 and 2, an internally-toothed or ring gear 34 isrigidly attached to one end face of the rotor 10. The ring gear 34 is inmesh with an externallytoothcd gear or pinion 36 which is rigidlyattached to the stationary end Wall 22 or the outer body 12.

From this construction, it may beobserved that the gearing 34 and 36does not drive or impart torque to'the shaft 26 but merely serves toindex or register the position of the rotor 10 with respect to the outerbody 12 as the rotor rotates relative to the outer body and removes thepositioning load which would otherwise be placed upon the apex portionsof the rotor 10.

As shown most clearly in FIGURE 1, the rotor 10 includes three apexportions 38 which carry radially movable sealing members 49. The sealingmembers 40 are in substantially continuous gas-sealing engagement withthe inner surface 18 of the outer body 12 as the rotor 10 rotates withinand relative to the outer body 12.

By means of the rotation of the rotor 1t) relative to the outer body 12,three variable volume Working chambers 42 are formed between theperipheral Working faces 44 of the rotor 10 and the inner surface 18 ofthe outer body 12. As embodied in FIGURE 1, the rotation of the rotorrelative to the outer body is counterclockwise and is so indicated by anarrow.

A spark plug 46 is mounted in the peripheral wall 20 of the outer body12, and at the appropriate time in the engine cycle, the spark plug 46provides ignition for a compressed combustible mixture which, onexpansion, drives the rotor in the direction of the arrow.

Also shown in FIGURE 1, there is provided in the end walls of the outerbody an intake port 48, and an exhaust port 50 in the peripheral wall18. As the rotor 10 rotates, a fresh charge is drawn into the workingchambers 42 through the intake port 48. This charge is then successivelycompressed, ignited, expanded and finally exhausted through the exhaustport 50.

All four successive phases of the engine cycle: intake, compression,expansion, and exhaust, take place within each one of the variablevolume working chambers 42 each time the rotor 10 completes onerevolution Within the outer body, and therefore for each revolution ofthe rotor, each working chamber completes a cycle.

The working faces 44 of the rotor are provided with cut-out portions orchannels 52 which permit combustion gases to pass freely from one lobeof the epitrochoidal inner surface 18 to the other lobe, when the rotoris at or near the top dead center compression position. Also, thecompression ratio of the engine may be controlled by adjusting thevolume of the channels 52.

Since the gear ratio between the rotor ring gear 34 and the outer bodygear or pinion 36 is 3:2, each time the rotor 10 completes onerevolution about its own axis 14, the shaft 26 rotates three times aboutits axis 16.

This invention is primarily directed towards a gas-sealing means 54located between inner faces 21, 23 of end walls 22, 24 of the outermember or housing and the end faces 11, 13 of the rotor which providesnew, novel and unexpected beneficial results.

In the description which follows, for the purpose of clarity, the gasseal of the present invention will be described with reference to oneend face of the rotor and the adjacent inner face of the end wall forouter body or member. It is to be understood, of course, that the otherend face of the rotor has a similar gas seal in sealing relation withthe inner face of the end wall of the outer body.

In accordance with the invention means are provided for insuring aneffective gas seal between the rotor end face and outer body end walland between adjacent chambers at the apexes of the rotor.

As embodied herein, the means comprises FIGURES 1-4, a gas seal 54 whichin transverse cross section is a substantially L-shaped seal having athin and flexible cross section. The seal can be made of any suitablematerial which has strength at elevated temperatures, resistance to wearat all temperatures and elasticity which remains substantially constantduring wide temperature differentials. Although beryllium copper-alloyin sheet metal form has produced excellent results, obviously, othermaterials having the characteristics hereinafter described will occur tothose skilled in the art and may be used in the practice of thisinvention.

As illustrated in FIGURE 6, the gas seal has a peripheral contour 56complementary with and substantially identical to the contour of theinner member or rotor 14 As shown in the illustrated form, this contouris essentially triangular wherein the sides 58, 59 and 60 of thetriangle are bent or bowed outwardly. For reasons more fully describedbelow it should be observed that in FIGURE 6 the gas seal width Ameasured from the inner surface 61 of the seal to the outer periphery 56of the seal is larger at the apexes of the triangular seal than is thewidth B measured from the inner surface 61 of the seal to the outerperiphery 56 of the seal intermediate the apexes of the gas seal.

As clearly shown in FIGURES 3 and 4 the rotor end face 11 is providedwith a generally triangular recess or slot 62 which conformssubstantially to the outer periphery of the inner member or rotor It).The width of the slot 62 is approximately five times the thickness ofthe gas seal 54. As mentioned previously the gas seal, as hereinembodied, has a cross sectional shape which approximates an L. As hereindisclosed for illustrative purposes, the short or rotor engaging leg 53of the L is placed into the slot 62; and maintained therein by meanshereafter described. A retainer or filler strip 64 having a widthsubstantially the same as the rotor engaging leg 53, is provided for thepurpose of cooperating with the rotor engaging leg of the seal and formaintaining that leg in tight frictional engagement with the recess 62in the inner member or rotor 10.

Additional means illustrated in FIGURES l and 5 show one preferred wayof maintaining the seal 54 and retainer or filler strip 64 within theslot 62 during the assembly process. As embodied herein, the outer edgeportion of the recess is bent or peened into engagement with the sealand retainer strip at desired locations 66.

Of course, it will be obvious to those skilled in the art that othermeans and methods may be devised for maintaining the gas seal inengagement with the rotor which do not depart from the inventiveprinciples explained herein. For example, it would be possible toeliminate the retainer or filler strip and merely provide a slot whichis suitably dimensioned so that one leg of the seal would fit snuglytherein. Similarly, the seal 54 and retainer ring 64 need not be peenedinto position but can be maintained within the slot 62 in the rotor bymeans such as screws or welding. Moreover, as will be apparent to thoseskilled in this art, means are not necessary to prevent the seal fromaxial movement during operation of the rotary mechanism but that thebending, peening or equivalent step is taken only for ease in assemblyand for maintaining the seal in its position during assembly of therotor.

It will be still further obvious that the gas seal 54 need not have along and a short leg to embody the principles of this invention but mayhave legs of equal lengths for example.

In accordance with the invention, means are provided for maintaining thegas seal in continuous sealing engagement regardless of variations inthe end walls of the outer body.

As shown in FIGURE 4, it will be observed that the gas seal hasextending substantially perpendicular from the rotor engaging leg 53 anouter member engaging leg 55. In the present preferred embodiment thisleg has been formed so that in its normal unobstructed condition it willform an angle of approximately 94-97 with the rotor engaging leg asshown in dotted lines in FIG- URE 4. This last mentioned feature takenin conjunction with the fact that, as embodied, the thicknesses of thegas seal legs, which range from /32 /16 of an inch, provide a flexibleseal which will maintain a tight gas-sealing contact with the outer bodyinner wall. In effect, a seal is provided which has an inherentresiliency or spring effect which negates a requirement for a separatespring means to insure engagement of the seal with the stator end face.Obviously, were a separate spring means provided, the seal would be moreexpensive and more difficult to manufacture and assemble.

Through use of the simple construction described herein, the seal ismaintained in firm, flexible sealing contact with the inner faces 21, 23of the end wall of the outer body and will retain this condition eventhough there might be variations in the surface condition of the endwall inner face. In other Words, the gas seal, owing to its inherentresiliency, will readily and automatically adapt itself to variations inthe end wall inner face of the outer body which are created byunavoidable manufacturing tolerances. In addition, when the gasesattempt to flow past the seal they will not be able to escape past theend portion of the seal but will be guided into the pocket 68, FIGURE 4,formed between the inner face 21 of the outer body engaging leg 55 ofthe gas seal and the rotors end face 11. As a result, these gases willforce the outer body engaging leg 55 into tight engagement with the endwall, and provide thereby a leakproof seal. At the same time these gaseswill force the rotor engaging leg 53 of the gas seal into gas sealingtightness with the rotor recess 62 thereby insuring against blowby, orescape of gases past the seal.

In accordance with the invention means are provided to insure a goodseal at the apexes of the rotor and to prevent blowby at the apexes.

The gas seal, as embodied, has a novel relationship with the apex seal50 of the rotor leading to beneficial and unexpected results. Withreference to FIGURE 3, there is shown a radially movable apex seal 4%which is biased in a radial direction by a spring means 41. As can beobserved in FIGURE 3, the gas seal 54 has a width A (FIGURE 6) such thatit extends to the end of the apex sealing means 40. By virtue of thisrelationship in conjunction with the gas sealing relationship be tweenthe apex seal 40 and the gas seal 54 there is a substantial reduction ingas leakage that has not been heretofore possible.

It should be observed also that providing a continuous gas seal incombination with a radial movable apex sealing means 41) substantiallyreduces the number of sealing elements and the number of surfaces to besealed. In known constructions where the gas sealing means has had asegmental construction, it has been necessary to provide a connectingseal means intermediate the apex seal and the end face gas seal. Theinstant invention eliminates the need for connecting seal means and yet,since the number of surfaces to be sealed are reduced, achieves aneffective seal which is simple and inexpensive.

In accordance with the invention, means are provided for minimizing thedestructive effects of high temperatures on the seal and contact of hotgases with the seal.

As hereinbefore observed, although the gas seal extends substantially tothe periphery of the rotor at the apex 38 of the rotor, the gas sealdoes not extend to the periphery of the rotor intermediate the apexes ofthe rotor. This relationship is graphically illustrated in FIGURE 6wherein the distances just mentioned are illustrated at A and Brespectively. This relationship of distances provides novel, beneficialand unexpected results.

As will be apparent to those skilled in the art, the peripheral workingface 44 of the rotor intermediate the apexes will, during the ignitionphase of the engine, be subjected to the extreme temperatures createdduring the ignition ph ase. Since, however, the gas seal does not extendto the periphery of the rotor at this point, the seal will not besubjected to highest level o-f'these temperatures and is less likely tosuffer from warping, burning or other destructive effects caused by suchhigh temperatures. On the other hand, the apexes of the rotor are notsubjected to the high ignition temperatures to which the peripheralportions are subjected and the seal can extend to the periphery of theapex seal, without damage, thereby achieving an effective andlonglasting seal which reduces undesirable blowby to a minimum.

In accordance with the invention, means are provided for forcing theseal into tighter sealing engagement with end walls of the outer body asthe temperature of the engine increases.

Still further novel, beneficial and unexpected results are achievedaccording to the invention as herein embodied according to the materialsused for the retaining or filler strip 64 and the rotor or inner member.If the rotor is made of steel, for example, and the retainer or fillerstrip 64 made of aluminum alloy, the filler strip will have a highercoefiicient of thermal expansion than does the rotor or inner member.Thus, when the filler strip is subjected to increased temperatures, itwill expand in an axial direction a greater amount than will the rotor,thereby forcing the outer body engaging leg of the gas seal into tightgas sealing contact with the inner face 21 of the outer member and withrecess 62 in the rotor. Obviously, other and different materials can beused for making the rotor and filler strips which achieve the beneficialand unexpected results noted above.

It Will be apparent to those skilled in the art, that the gas seal asherein embodied has the advantages that it can be made of sheetmaterial, such as beryllium copper, and can be formed by a simplestamping operation performed in a conventional stamping machine. The gasseal is wear resistant, flexible and yet resists distortions caused bytemperature differentials thereby insuring effective and longlastingsealing contact. The seal, as herein embodied, has a novel continuouscontour reducing the number of scaling surfaces. The seal according tothe present invention is assembled by an expeditious and simple snap-inaction which reduces the number of parts and the cost of assembly.

It will be readily apparent to those skilled in the art that theprinciples and advantages of the instant invention can be realized byvariations in the embodied invention which do not depart from theprinciples utilized therein.

What is claimed is:

1. A gassealing means for use in rotary mechanisms having asubstantially triangular periphery wherein the sealing means is wider atits apexes than it is intermediate the apexes and includes two engagingportions giving the seal an approximately L-shaped transverse crosssection.

2. A gas-sealing means as defined in claim 1, wherein the angle betweenthe engaging portions has a range of 94 to 97.

References Cited in the file of this patent UNITED STATES PATENTS1,617,863 Planche Feb. 15, 1927 1,636,486 Planche July 19, 19271,891,424- Kirkpatrick Dec. 20, 1932 1,896,378 Rockwell Feb. 7, 19332,013,499 Mechenstock Sept. 3, 1935 2,098,084 Carlson Nov. 2, 19372,328,676 Rich Sept. 7, 1943 2,880,045 Wankel Mar. 31, 1959 2,979,042Kentele Apr. 11, 1961

1. A GAS-SEALING MEANS FOR USE IN ROTARY MECHANISMS HAVING ASUBSTANTIALLY TRIANGULAR PERIPHERY WHEREIN THE SEALING MEANS IS WIDE ATITS APEXES THAN IT IS INTERMEDIATE THE APEXES AND INCLUDES TWO ENGAGINGPORTIONS GIVING THE SEAL AN APPROXIMATELY L-SHAPED TRANSVERSE CROSSSECTION.